How should I address my guardian to it?

As you may have heard of my previous questions:

I feel around the clock, no matter where, watched!

I did not think it was bad, but now things are getting worse!

I'm already used to talking to myself and thinking that someone is listening to me and that when I look out and smile, somebody sees me and maybe smiles back, but I get scared of it.

I had almost a panick attack last night because I thought someone was in the house (which I had before, just without fear) and that the person was watching me extra heavily this time around.

Today / Straight it got worse again.

I was in the bathroom and the blinds always have such a small slit which is fluted in the middle because they always get stuck.

When I turned off the light and wanted to go out to my room, I did not see the light through the cracks (yes, they were there).

When I got out quickly, I had to go back in 5 minutes to wash my hands (I had eaten something).

I was out of fear the light left out and all the time staring at this slot. I've always had the feeling that there's a person standing there and I've seen 'the shadow' in between (I know it was probably just imagining) and when I just looked away and then back down I have not seen the light again.

I was about to run away when I saw something move and then slowly the light came back.

I went out quickly and when I closed the door (with my back to the hallway), I felt as if someone had touched my back.

I almost screamed out of angst and quickly turned around. Since nobody stood behind me, I quickly went into my room (where I write this now).

Now I wanted to ask how to tell my guardian (grandmother) how I feel.

I know she will not believe me and says I'm too much on the phone / laptop!

She is of the opinion that psychologists only cause further problems and I do not want to go to school psychology (I almost had to go there, because I had scratched myself for a reason).

Alone I can't go anywhere, because I can't leave the garden without a parent or guardian (except when I have to go to school, but I'm going there and picked up)

Since I'm only 12 (will be the end of August 13), I'm probably accused again that everything is just a phase.

PS: I distract myself with videos the rest of the time so I would not think about it.

I would recommend that you go to a trustworthy person who you believe can help you in any way and I would recommend going to the psychologist (there's nothing wrong with that) and yet you should talk to your grandma if she does you believe is good, if not then you have not lost anything and then can do what I have recommended but the way you want to go you have to decide for yourself.

Ps: I would miss out on thrillers and horror movies first